diff --git a/ChangeLog b/ChangeLog
index 7a07a17f35..b6a082a31f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Feb 20 16:22:53 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* file.c (rb_file_flock): use rb_thread_io_blocking_region for the
+	  time being.
+
 Sun Feb 20 05:33:17 2011  Ryan Davis  <ryand-ruby@zenspider.com>
 
 	* lib/minitest/*.rb: Imported minitest 2.0.2 r6207.
diff --git a/file.c b/file.c
index 00a2a0c7ee..b743a32fca 100644
--- a/file.c
+++ b/file.c
@@ -4058,7 +4058,7 @@ rb_file_flock(VALUE obj, VALUE operation)
     if (fptr->mode & FMODE_WRITABLE) {
 	rb_io_flush(obj);
     }
-    while ((int)rb_thread_blocking_region(rb_thread_flock, op, RUBY_UBF_IO, 0) < 0) {
+    while ((int)rb_thread_io_blocking_region(rb_thread_flock, op, fptr->fd) < 0) {
 	switch (errno) {
 	  case EAGAIN:
 	  case EACCES: